Venoms of sea snakes, (Hydrophiidae), contain potent neurotoxins. As compared with land snakes, sea snakes and their venoms have not yet been extensively investigated. In order to understand the mode of action of sea snake venom toxins, we plan to isolate them in highly purified form. Their chemical, physical, toxicologic, and pharmacologic properties will be investigated. At present, there is only one commercial antivenin for sea snake poisoning. We tested the neutralization capacity of this antivenin against the venoms of sea snakes captured in different parts of the world. The antivenin neutralized the venoms of Pelamis platurus from Costa Rica, Praescutata viperina from Thailand, Laticauda semifasciata from Philippines and Laticauda laticaudata from Japan. We hope that our research will contribute to the long-range objectives of chemotherapy for sea snake poisoning.